The present invention relates to a method and an apparatus for detecting ply separations and other deficiencies in carcasses prior to the retreading thereof.
It is of great importance to carefully inspect all used vehicle tires in respect to ply separations and other deficiencies before they are retreaded, since otherwise, many of the finished tires have to be rejected. In most of the present retreading plants there exists and excessively high percentage of rejection or cassation, which is due to the fact that all deficiencies are not discovered during the inspection of the tires or carcasses carried out prior to their retreading. In many instances, such deficiencies become visible only during the proper retreading process wherein such deficiencies are greately magnified. The most common deficiency is the ply separations which become visible only after heating.
The first step of the retreading process usually consists of heating and drying the carcasses in a drying chambwer for example, in which they are heated to about 60.degree.-80.degree. C. for a day and night or more to remove inherent moisture. After the heating and drying treatment the carcasses are moved through an inspection device for detecting present deficiencies such as ply separations. The heating operation carried out in the above manner has proven unsatisfactory in failing to reveal all ply separations, resulting in the excessive amount of rejected retreaded tires.